Related subject matter is disclosed and claimed in co-pending U.S. patent application Ser. No. 08/569,346, filed by S. Joseph Campanella on Dec. 8, 1995, now U.S. Pat. No. 5,835,487; in co-pending U.S. patent application Ser. No. 08/746,018, filed by Robert L. Johnstone et al. on Nov. 5, 1996, now U.S. Pat. No. 5,898,680; in co-pending U.S. patent application Ser. No. 08/746,019, filed by S. Joseph Campanella on Nov. 5, 1996, now U.S. Pat. No. 5,867,490; in co-pending U.S. patent application Ser. No. 08/746,067, filed by S. Joseph Campanella on Nov. 5, 1996, now U.S. Pat. No. 5,870,390; in co-pending U.S. patent application Ser. No. 08/746,020, filed by S. Joseph Campanella on Nov. 5 1996, now U.S. Pat. No. 5,864,546; in co-pending U.S. patent application Ser. No. 08/746,069, filed by S. Joseph Campanella et al. on Nov. 5, 1996, now U.S. Pat. No. 6,115,366; in co-pending U.S. patent application Ser. No. 08/746,070, filed by S. Joseph Campanella on Nov. 5, 1996; in co-pending U.S. patent application Ser. No. 08/746,071, filed by S. Joseph Campanella on Nov. 5, 1996; and in co-pending U.S. patent application Ser. No. 08/746,072, filed by S. Joseph Campanella on Nov. 5, 1996, now U.S. Pat. No. 6,015,315; all of said applications being expressly incorporated herein by reference.
The present invention relates generally to the transmission and reception of information, and is particularly concerned with a system for providing real-time audio, video and data transmissions to airline passengers.
Modern aircraft provide passengers a variety of entertainment programs, including movies, science features, advertising, news, music and other types of video and audio programs. However, all of these programs are pre-recorded (usually on magnetic tape), sometimes days or months prior to the commencement of the flight. As a result, while today""s airline passengers are increasingly able to take advantage of high-technology services, such as in-flight telephone calls, they are cut off from live news, sports events and other events that occur during the course of a flight. Thus, it is quite common to witness airline passengers rushing to the nearest television set immediately after their flights have landed at an airport, particularly if a major news or sports event is taking place. In some cases, even that option is not available because the event is taking place at a distant location and is not of local interest at the passenger""s destination.
Although aircraft are capable of receiving radio and television broadcast transmissions from terrestrial sources, this is not a practical way to provide real-time news and entertainment programs to airline passengers. One problem is that the effective range of most commercial radio and television broadcast stations is limited to a distance on the order of 100 kilometers. For a turbine aircraft flying at a speed in excess of 750 kilometers per hour, it is apparent that the aircraft will be within range of a terrestrial broadcast station only for a short period of time. This time interval will typically be less than the duration of most types of news and entertainment programs. Another problem with receiving terrestrial transmissions is that the relative distance between the aircraft and the broadcast station changes quickly as the aircraft travels along its flight path, resulting in large variations in signal strength and transmission quality. Moreover, for terrestrial transmissions which are capable of being received over long distances, the blocking effect of the earth""s horizon can interfere with proper signal reception.
In co-pending commonly-assigned U.S. patent application Ser. No. 08/569,346, filed by S. Joseph Campanella on Dec. 8, 1995, now U.S. Pat. No. 5,835,487, and in the other co-pending applications identified previously, a new global digital broadcast system is described. The system employs three geostationary satellites, each having three contiguous downlink spot beams covering large land masses. The primary intended mode of reception is a portable radio receiver, with the ability to select one of several hundred 16 kilobit per second (kbps) prime rate channels. These channels can be used individually for audio or text broadcasts, or they can be combined to form digital streams as wide as 1.5 to 2.0 megabits per second (mbps). Depending upon the mode selected, the uplink signals for these broadcasts can originate either from a central hub located at a discrete site within the uplink coverage area of a satellite, or from a plurality of individual Very Small Aperture Terminals (VSATs) distributed throughout the uplink coverage area of the satellite. Underlying the present invention is the recognition that a satellite-based digital broadcast system of this type can be used to provide real-time broadcast programs to aircraft in flight, without suffering from the disadvantages and limitations of the prior art.
In view of the foregoing, it is an object of the present invention to provide a system for delivering real-time broadcast programs to aircraft passengers which does not suffer from significant range limitations, signal strength variations or horizon blocking problems.
A further object of the present invention is to deliver broadcast programs to aircraft on multiple channels, so that airline passengers can select from among a large number of different programs.
A further object of the present invention is to provide both audio and video broadcast programs to airline passengers, as well as other types of information delivery services.
A still further object of the present invention is to make it possible to restrict certain broadcast programs so that they can be received only by certain aircraft or groups of aircraft, so that broadcast programs tailored to specific airline companies can be reserved for use by those companies.
These and other objects of the present invention are achieved by using a satellite-based digital broadcast system to provide real-time broadcast programs to aircraft in flight. Because of the wide area of geographic coverage that can be obtained with a satellite, the aircraft will remain within range of the satellite for a sufficiently long period of time to allow most types of live broadcast programs to be received in an uninterrupted manner. Moreover, due to the great distance between the satellite and the aircraft (particularly in the case of a geostationary satellite), problems arising from signal strength variations and horizon blocking are minimized.
In one aspect, therefore, the present invention is directed to a system for providing real-time broadcast programs to aircraft passengers. The system comprises at least one terrestrial broadcast station for transmitting a plurality of different broadcast programs, and a relay satellite for receiving and retransmitting the broadcast programs. The retransmission from the relay satellite occurs on a time division multiplex (TDM) downlink with different ones of the broadcast programs being transmitted on different TDM channels in the downlink. A broadcast receiver is carried on board the aircraft, and includes a demultiplexer for demultiplexing the TDM channels to reproduce the original broadcast programs. Preferably, the broadcast receiver is adapted to receive and reproduce both audio and video broadcasts, as well as to provide other types of information delivery services. In a preferred embodiment of the invention, at least one of the TDM channels contains an encrypted broadcast program, and the broadcast receiver is adapted to decrypt the encrypted broadcast program so that the program can be restricted to a specific aircraft or airline.
In another aspect, the present invention is directed to an on-board broadcast receiver for providing a plurality of real-time broadcast programs to aircraft passengers. The broadcast programs are transmitted to the receiver by a satellite on a time division multiplex (TDM) downlink, with different ones of the broadcast programs being transmitted on different TDM channels in the downlink. The broadcast receiver comprises a satellite antenna carried by the aircraft for receiving the TDM downlink, a demodulator coupled to the antenna for demodulating the TDM downlink, and a demultiplexer coupled to the demodulator for demultiplexing the TDM downlink to reproduce the original broadcast programs.
In a still further aspect, the present invention is directed to a method for providing real-time broadcast programs to aircraft passengers. The method comprises the steps of transmitting a plurality of different broadcast programs from at least one terrestrial broadcast station to a relay satellite; retransmitting the broadcast programs from the relay satellite to an aircraft in flight, such retransmission occurring on a time division multiplex (TDM) downlink signal with different ones of the broadcast programs being transmitted on different TDM channels in the downlink signal; and receiving and demultiplexing the downlink signal on board the aircraft to reproduce the original broadcast programs.